Shock absorber



Patented Nov. 3, 1953 SHOCK ABSORBER Edwin F. Rossman, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application August 27, 1951, Serial No. 243,816

Claims. l

This invention relates to an improved hydraulic shock absorber.

It is among theobjects of the present invention to provide an hydraulic shock absorber of the direct acting type, compact in design, sturdy and of minimum weight so-as to be adaptable for installation in airplanes, helicopters, or other aeronautical vehicles in which lightness and strength are important factors.

Further objects and advantages of the present invention will be apparent from the following description. reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawing: Y

Fig. 1 is a longitudinal, sectional view, substantially double size, of a direct acting hydraulic shock absorber particularly adaptable for use in aeronautical vehicles.

Fig. 2 is a half section, similar to Fig. 1, show'- ing the relatively movable portions of the shock absorber in other operating positions.

Referring to the drawing, the numeral designates the cylinder of the shock absorber, opposite inner ends of which are provided with interioil screw threads. Each end of the cylinder 20 has a head member secured within it, the one head member being designated by the numeral 2| and secured in the cylinder by the clamping collar 22, threadedly received by the cylinder, the other head member, at what may be termed the lower end of the cylinder, being designated by the numeral 23 secured within the cylinder 20 by the collar 24 threaded in this end of the cylinder.

The head member 2|, hereinafter referred to as the upper cylinder head; has a central opening in which a bearing sleeve 25 is provided for purposes to be described. A cylindrical extension 26 is formed on the upper head 2|, this cylindrical extension extending outwardly from the cylinder 20 and at its extreme outer end providing a portion 2l which forms one mounting element for the shock absorber by means of which the shock absorber is attached to one of the relatively movable members whose movement it is adapted to control. The tubular extension 26 is closed at its outer end by a screw plug 28 which is adapted to be removed to render available certain interior elements within the extension 26 for adjustment purposes as will later be described. Spaced openings 29 and 30 are provided in the annular wall of the cylindrical extension 26 in order to provide communication between the reservoirv3| and the interior of the tubular extension 26. Thisreservoir 3| is formed by an outer tube 32, greater in inside diameter than the outside diameter of the cylinder 20, to form an annular chamber around the cylinder which is part of the reservoir 3 I, this tube being secured to a disc-like structure 33 which is attached to the tubular extension 26 by means of screws 34, a resilient or compressible packing gland 35 being provided between member 33 and the cylindrical extension 26 to prevent iiuid leaks at this point. The other end of the reservoir tube 32 is secured to the lower end of the cylinder 20 in any suitable manner, having a packing ring 36 provided therebetween to prevent fluid leaks at this region. A similar packing ring i k31 is located between the head member 23 and the cylinder in order to prevent fluid leaks between the cylinder head 23 and the cylinder.

The lower head member has a central opening of similar diameter and coaxial with the central l opening in the head member 26, this central opening in head member 23 also being provided with a bearing sleeve 40.

Both head members are provided with means forming communication between the reservoir 3| i and the interior of the cylinder. Head member 2| has a series of openings 42 providing this communication. The inner wall of the head member at which opening 42 terminates has an annular ridge 43 surrounding the opening providing a seat upon which the valve 44 is yieldably urged by a spring 45 interposed between said valve and an abutment ring 46 resting upon a collar secured to the head member 26. As illustrated in Fig. 1, this valve 44 prevents any uid from passing from the ycylinder chamber to the reservoir but on the contrary will, when necessary, be moved to establish a replenishing fluid iiow from the reservoir through passages 42 into the interior of the cylinder. Likewise head 23 has a series of passages 50 in communication with the reservoir through side openings 5|, the head member 23 providing an annular valve seat 52 around each opening engageable by the ring disc valve 53 under theinluence of a spring 54 which is interposed between the valve 53 and a rigid collar secured to the head member 23. This valve 53, like valve 44, will prevent any fluid from passing from the cylinder to the reservoir but on the -contrary will open and permit a uid flow from r`the reservoir through the passage 5| and the passage 50 into the cylinder if iiuid replenishment is necessary within said cylinder.

An imperforate piston reciprocative within th cylinder divides the `cylinder into two working chambers and 6|, the former being termed the upper chamber and the latter the lower working chamber of the shock absorber. This imperforate piston may be formed integral with a hollow piston rod 62 or, as shown in the present drawing, the piston may be an assembly of the parts secured to the hollow rod 62 so as to be movable therebxn 1n the present'1` drawing, the imperigt'e isfshown as :an two in nine members sa and t4 heid together by clamping screws or studs 66. Annular grooves in the piston members 63 and 64 cooperate to form a single groove which encompassesmand clasps an outwardly extending annular ilange 66 on the tubular rod 62 whereby said piston portions 63 and 64 are clamped tion on the rod by screws or studs 65 will immovably secure the piston 'en the hollow rod. Any suitable packing ring 61 is clamped between abutment rings sa between the two 'prtions 63 and 64 to provide a substantially leakproof rubbing contact by the piston 'upo'n the Interior wall`f the cylinder v20. -In'case -tl'ie ini- 'periorate piston `designated for purposes "of *del block secured 'to 'or formed integral with the llOIlUW piston 'rod '62 'any 'Suitable 'pistn "rings,

"if required, maybe provided inthe outer annular wailof 'the Ipiston.

`Compitehiess and weight 'are ob'- tined bytprov'iding the 'fluid flow control mechwithin the hollow'piston rod 62, saidmechanisin lregulating `predeterniinately the transfer ot `iluili between the 'cylinder chambers 60 'and '9| 'asthepiston'isireciprocated within the cylinder. 'Rod IV62 `has openings '80 in its side wall adiacent the upper'end of `the piston A'l0 so as to provide. communication "between the 'cylinder chamber above 'the piston `vand the vinterior of 'the hollow rod`62. ASimilar openings v8| /are provided.' in the annular wall" of the 'hollowf piston rod '62 forming communications between the lower cylinder chamber 6| and the interior of the hollow rod 62. 'AAplug liisimmovably secured `w'ithin -theihollowpiston rod 62'1n any ,suitable manner. This plug liasradlalpassages 96"algn ing;and"communicating withtheopenings 00 in the hollow rod'62'fand'similarradial passages 81 aligning :andcommunicating with'the openings 6| 'infs'aidtrocL "Plug 65'has acentral recess from :the upper end surface 'of the plug'ad terminatingirrradial'passa'ge` Ii'l` so ags'to 4'communicate therewith. VIt will, vvof course, be iindrstood that 'the 'central passages 08 in plug il. to reach `-the 'passage 81, also communicates with 'the radial passage 96,"so that these `radia1 passages'66 and ,91 `in the l'plug vwith theaid otthe openings |30 and'8l, respectivelyyin'tne hollow' rod, form 'communication between there- 'spective cylinder chambers and the central i passage 09 in `plug 65. At 'a point "between 'the radlalfpassagesii and 61, the diametrical vside ofthe recess 96 is"reduced,thereby providing Van annular shoulder 'within the said recess'forniing "a 'valve v"seat therein. A `Vtubular valve v90 is slidably supported "within the recess 'f 60 oi. the plugfth'e valve 90"having"a reducedidiani'eter portion '9| adjaeent'its inner' end which'foi'nis the annular chamber 92 within thelplugi. The reduceddiameter 9| of vvalve`9il'h`asI an outwardly extending, annular ilange'93fadjacent its' ed, Said flange' providing theA portion' of -the valve 90 which engages-the valve seat09 under the ln'ue'nce of'a `c'iil'sprlng` 955'i'terp's'ed'1between'nnfabutmenteeiiar mi the 'vente soamifa. h'dme'mber 96"th'r'ea'dedly receivedl at the i luppei` end of the hollow rod 62. Annular wall of the smaller valve portion 9| of valve 90 has an opening 91 therein which lcommunicates with an orifice 98 provided in the cup-shaped plug 99 immovably secured within the smaller diameter valve portion 9|. The end wall of the cup-shaped element 99, secured within the valve portion 9|, has ibrmc l siml` 'GB 6i' d bielet'ermined site relative 'to the 9i. These orifices |00 and 96, with the assistance of the opening 99 in the valve portion 9|, provide a constant gniinunication between the cylinder chambers 6 and 6| while said valve portion 93 engages 'the Hive y"seat 99 and therefore initially restricts the t'sfer or mid in either direction between *chambers before the valve is :moved by duid pressure. The hollow valve 90 has screw plug |02 threadedly received at its tend, this screw plug providing an orifice |03 which forms a restricted communication be- 'tween th'e interior of `the valve 90 and the Ispace within the hollow piston rod 62 between the valve V91| and 'the end closure member 96 for-said nod.

The end closure -m'ember 96 at the -upper end of the hollow rod 62 -'has a through passage |96 connecting the 'interiorof 'the hollow rod `69 with the interior o'f the tubular 'extension V26 which. in turn, `is lin'communication with the reservoir 3| through the opening 29 `in s aid ltubular 'extension. This 'closure rmember 96 has 'a transverse slit |04 which forms two yrelatively moving parts in said closure member. The outer upper end'of -the closure member has a'central lrecess. the vinner portion of which isof Yone ldiameter as at |06, the inner intermediate vportion being threaded -asat VAportion r|01 andthe outer portion thereof'being-shapedtohafve flat-sides ipas-fcr instance, a square or rectangular 4recess into which a wrench may be inserted -for-'the Vpurpose of 'turning fthelclosure `member 96 which, as --has becn'described, 'is lthreadedly received by the hollow rod 62. The vthreaded `interior'oi vthe I'recess in the closure -meinber -96 receives a plu'g '|09 having -a wrenching-receiving recess at vits' outer endsand 'afpilot -end portion fitting Awithin Athe portion |06 in the recess of the head lmember $6. -When theplug-IM is turned into thecloeure end-member 96 and its pllot=portion engages the bottom of "the recess therein, lthe two `portions of'the closure member96yprovided'by'thetransverse-slit |04, arebiased-and thus rigidly 'held so thatthe-'closurefmemberis immovably pecured to the'tubula'r rod 62. Closure member 96 `forms-an abutment for the one y'ndbif the spring 95, whose other end engages the valve90 and-yieldably urges it so that the portion 93 thereof fis vyieldably maintained Aupon Ithe fseat 89. VIf the Ytension'offtheV spring 95's -to'be afdjusted, --plug |09 isfscrewed fout -of 1 the end ciosure'member 96 rto-reiease the tension'oh'tlie split-*portion -of the'member, 'thereby' permitting thefinsertion of 'a'ftool-inthe recessed-end |90 of' said-closure' member-f96 for :purposes 'of turningfit relatively to the.- rod 62 and-thereby obtaining "tlie -desired adjustment 'after which `vthe plug i09 is again-operated to tensionthe'closr'e memberfsi 1 in order -to lock: il:v into adjusted Alisositionjinthe h'ollow'ro'd 62. The/recessed portion |06'ofthe end'closure'memberf96 -is rndered@ 'accessiblebythe removal of plug L29 from the-'cylinder :closure head 2 6.

which, this portion of the device may be attached to the other member whose movement the shock absorber is adapted to control. e

Fig. 1 shows the shock absorber in the completed or contracted position while Fig. 2 shows the shock absorber in the intermediate or partially expanded position. When separating movement of the two relatively movable members, between which the shock absorber is attached, occurs, the portion of the shock absorber comprising the cylinder closure member 2| and its tubular extension 26, together with the cylinder 20, reservoir tube 32 and the lower cylinder closure member 23, will be moved and thus member 23 will approach the piston 10, thereby reducing the cylinder chamber 6| ,and exerting a pressure upon the iiuid therein while the fluid chamber 66 will be enlarged. As pressure is exerted upon the iiuid within the chamber 6|, it will be forced through opening 8| into hollow rod 62, radial passage 81, in the plug 85, into the -recess 88 of said plug, against the valve 90, the initial fluid fiow being restricted by passing through the orice |00 and communicating orifice 98, opening 91 in valve 90, into the annular space chamber 92, thence through radial passage 86, in plug 85, opening 80 in tubular rod 62, into the now enlarging cylinder space or chamber 60. The restriction to the transfer of uid from chamber 6| to chamber 60 by the orifices |00 and 98 causes the shock absorber to offer a predetermined resistance to the relative movement of the members between which it is secured. If the fluidpressure within chamber 6| is of such a degree that it cannot properly be relieved by the aforedescribed restricted fluid flow, then the excessive pressure acting from chamber 6| into the valve recess 88 against'valve 90 will move said valve against the opposing effect of the spring 95 to lift the valve portion 93 from engagement with the valve seat 89 for establishing an additional restricted fluid iiow through the opening presented between the valve 93 and the seat 89, thereby establishing a restriction to the transfer ofk fluid between chamber 6| and chamber 60 of the cylinder in accordance with the fluid pressure within the chamber 6I.

If, on the other hand, the shock absorber, as shown in Fig. 2, is moved in the opposite direction by the approaching movement of the two relatively movable members between which the shock absorber is mounted, then the piston 10 and the cylinder closure member 2| are moved to approach each other, causing the piston 10 to exert a pressure upon the fluid within the upper cylinder chamber 60 in response to which the fluid flow from chamber -60 through opening 80 in the hollow rod 62, radial passage 86 into the annular space 92 provided within the recess 88 of the plug 85, the fluid then passing through opening 91, communicating orifice 98, orifice |00 through the communicating recess 88 and radial passage 81, opening 8| into the cylinder chamber 6|. The restriction to the transfer of fiuid from chamber 60 to 6| is the same as the restriction to the reversed flow between chamber 6| and 60 as aforedescribed and therefore the shock absorber will ofer the same initial resistance to the movement of the two relatively movable members. If the pressure within chamber 06 exceeds the degree at which the orifices may completely relieve the pressure in said chamber, then valve 90 again is actuated to establish a pressure relieving flow from chamber 60 into chamber 6l. f

As shown in the drawing, the upper, annular end wall of space 92, provided by valve 90, is of greater area than the opposed, lower, annular end wall provided by the iiange 93 on said valve. Thus this difference in opposed areas will render the fluid pressure eiective to move valve 90, against the opposing effect of spring 95, so that a pressure relieving fluid flow is established past the valve seat 89 now disengaged by the valve flange 93, from chamber 60 into chamber 6|.

`It will be noted that this single valve 90 acts to control iiuid flow in both directions between said chambers. Valve 90 is moved in the same direction by excessive fluid pressure in either chamber 60 or chamber 6|.

Valves 44 and 53 are replenishing valves, compensating for any fluid losses in chambers 60 or 6|, respectively, caused by fluid leaks from said chambers. If there is a iiuid deficiency in either chamber, the piston will, as it moves'away from either valve, cause fiuid to be drawn from the reservoir and into the chamber through the respective, `openkvalve.

The orifice |03 provides for a fluid pressure escape in case temperature changes cause an expansion of fluid within the 'chambers 60 or 6|. This prevents such pressures from opening or holding open valve 90 and consequently upsetting the immediate iiuid flow control in response to shock absorber action. Thus when fluid pressures, caused by temperature responsive fluid expansion, exist, such pressures may be eliminated by escaping through the orice |03 to the reservoir, thereby keeping` valvey 90 in normal seated position, ready for immediate and full fluid flow control when the shock absorberis actuated.

While the embodiment` of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

l. An hydraulic shock absorber consisting of a cylinder provided with a rod guide at each end; a reciprocative piston in the cylinder forming two work chambers therein, said piston having a central tubular portion extending from opposite sides thereof, each portion being slidably supported in a rod guide, said tubular portion having an opening in the wall on each side of the piston, said side openings providing communication between the work chambers through the tubular portion of the piston; a closure member at each end of the tubular portion of the piston; and spring loaded valve mechanism in the said tubular portion, rfor restricting the iiow of fluid between the cylinder work chambers, said valve mechanism consisting of a spring loadedy valve slidable in said tubular portion and having' surfaces exposed to the pressure of the fluid in both cylinder work chambers and thus being movable in one direction byfluid pressure in either work chamber for establishing and varying the restriction to fluid flow between said chambers in accordance with the fluid pressure.

2. An hydraulic shock absorber consisting of a cylinder provided with a rodguide at each end; a tubular rod slidably supported by said guides and having an imperforate, disc-like, outwardly extending flange slidably fitting the cylinder and forming a reciprocative piston therein which divides the cylinder into two'working chambers; a hollow plug immovably secured within the tu,

7 blarfredlanii havinganuxmemannulavshouider providing a valve seat; closure'merbersateach end 1dr I said rod; an opeirrg'in the 'wall-'of the tubular rodfadjacenteachaen'd of the piston, each opening aligning vwith -a -r'orrespranding opening ln '-the l plug andcommunicating 'withthei interior 'f `said 'plug Vvwhereby .thevworkin'g -l'rarriierers s are in communication' With-each otherthrough said plug; la valve slidably -supported in -the *plug Aand urged toward v`:the seat in 's-idplugforrLrestricting fluid ilowbetweenlsaid cylinderf'ehamrbers; f and asp'rin'g interposed betweensaidwalve 'and fa rod'flosuretmember and pmvidingeapre- 'determined 'opposing :force ftof-mcvemcntsv f #the 'valve fromf said seatifin'uesponsetoiluid 'pressure i inl-each cylinder working chamber.

3. An hydraulic shock absorber-Tconsisting 'of plcylintierffprovided f-W-itlfr aI rodv guide at' eaclrend; a tubular -rorifslidably fsupported by Lsaid guides vand having-fanilimperforate, 'outwardlyfexteriding `annular ilangefsl-dably fitting jthecylinder #and "Iorln'irrgf-a-- pistonthereinwhich divides the cylin- -kier into twowoifl'ring chambers/closure members iat lthe ericislf the @tubular rod; y-a plug immovably secured within the tubular rod, said plug Vhaving-an axial recess extending 'from one fendtheretf in -`-which1an annular shoulderi forms a valve-seat; j'radialipassages :leading litem-said axial 'recess4 on; each side o'f the valve-seat xto openings inl-the; tubular-rod communicating with 4"the respectiveworkmg chambers; a=valve slidably supportedin'said axial recess-for restrictingliiuid transfer 'through :said:` plug `betweenthe working chambers inf responseE to piston Y reciprocation; a

adiacentirod closure ememberg-urgi-ng .thel valve upon-the seatwithin the plug -for predeterminatelly opposing movement ofthe valvefromv said -seat by fluid pressure in either working chamber;-and 4means infsaid adjaeentclosureImember-for ad- 'iustatblyl securing -it -in= said'v4 rod.

LA. hydraulic :ishoekabsorberr .consisting` -of a cylinder having a closure providingfa'rod'guide at each end thereofanrimpei-fomte ipistoni dividingithe. .cylinderl'into'ltwo workings-chambers, said piston having .a hollow r'rodl'slidably-asupportedzntheilrodl'guide; aclosures atfea'chflendr of thezihollow.lpistonzlrod;f.fimmovablezzhollow.fmeans zwithin :the :pistoni rod,isaidf hollow meanshaving side 'coopemting withe openings ini. the piston: rod-i ,for:providingzcommunication .between .the two `.working chambersand .arspring-lioadod valve inthe saidzhollowmeans operative ixrfone direction .by fuid i: pressure z `in ,.zeither working chamber. for :controlling;.iluidl flow: .between =said chambers.

5. An hydraulic'. shock .f absorberoconsistingcof a cylinderhavingf a. closure member..at.eaoh1end, each closure. member providing-.af rod: guidelthe one closure member having-za cylindrical `extension coaxial of; its Vrod'. guide. and -closed'L at" its end; Va tube'. secured` to '-bothl closure `.members and forming a duid mservoiraboutsaid cylinder; an. impertorate: piston` .dividing the cylinder `into two working :chambersfv and 'having a'fJhollow'rod slidably L supported .infxaid 'rod Lguides; Aa solid plug secured inoneriendnof'thehollow-romand an apertured plugadiustably securedfintheV other end. of the rod; openings.l fin fthecylindrical#Y extension. of the one closures-:member 'providing communica-tion. betweenfithe reservoir and-.the interior of thelsaid-cy'lindriear extensionpa :plug immovably 1 secured. awithinxthe' fhollow rodvsubstantially intermediate-:the zendf plugs therein smlfrhawirigamaxial4 recess one -end of #the `axial fplug `and `short of the other Zend @thereof and having Van interior :.valveeat; yradial -openings communicatingwvith rthe -axial recess :and with openings inlthe hollow rodladjacenteach side-of thepiston, wherebysaid working cham- Abers are in communication with each .other 4throughl-the Yaxial recess; and a Yspring loaded, -oriiiced .valve slidable in .the 4axial recess .and urged upon -the valve-seat therein, said valve being yoperative away from said valve-seat in response to Yfluid pressure in either lworking Achamber to control the duid .ilow between .said chambers and Lthe lreservoir in accordance with the fluid pressure in said chambers.

f6. 4.lin-hydraulic shock absorberconsisting of a cylinder having'a-closure member at each end, each closure member-.providing a rod.y guide, .the one closure member having acylindrical extension coaxial of its rod guide and closed `at 'its end; a, tube secured to both closure members and' forminga uid reservoir about said cylinder; an imperforatepiston dividing the cylinder-into two-working chambers and having4 a hollow rod slidably supported in `said rod guides; .a 4solid plug securedin one end of the hollow rod and `an 4apertured plugadjustably .secured in the .other end of the rod; openings inthe cylindrical 4extensiontof the one closure member providing communication between the reservoir .and the interior of the'said .cylindrical extension; a plug 'immovably securedwithinthe `hollow rod substantially intermediate v the end plugs therein and having an axial recess from one end of the plug'andfshort of the other end thereof, said axial recesshavingan annular ledge forming n -valve-seat; .radial .openings vin the plug communicating withtheaxial recess and with open- :ingsingthe'hollow rod-adiacent eachside of the piston,r wherebysaid working chambers are in communication Awith each other through the recess the plug; and a spring loaded oriilced valve slidable f-in .the axial recess .aand urged upon the valve-.seat -therein, :said Yvalve A.being .oriiced and thus voperative, without= movement, '.tlrst to establish a constantly restricted 'iluid ilow between -the working chambersthen to be moved in one direction in response to increased fluid pressures :in either :working chamber .for establishing an additionalfrestricted fluid :flow into the companion: chamber, 1 the .orificed valve being operative.aiso,without movement, to establish a pressure relieving iluidow from said working chambersnintof the open-.cylindrical extension of the Aonefclosure :member and the Areservoir in respousev to: thermal expansion of'the'iluid in said chambers.

7.'A- device 'in accordance with aclaim 5 in .whicheach Ycylinder -closure member has passages through which the adjacent working chamberand the fluidiv reservoir areconnected anda spring loaded valvecontrolling each passageand` operative to` establish .a replenishing 'iluidiflow from the reservoir Vinto the respective cylinder chambersas the closure members are moved away from the piston.

8. 'An hydraulic shock absorber consisting of a. cylinder having a closure at each end, each closuresproviding a rod guide; an imperforate piston dividing the vcylinder into two iluid`displacement 'chambers-said pistonhaving a hollow rod slidably 'supported-in said rod guides, the one end of lthei'od' beingiclosed, 'the other end having an apertured -plug-adjustably secured therein and 4openings-in thelhollowrod adjacent each lside 9 of the piston; a uid reservoir in communication with both displacement chambers and with the interior of the hollow 'rod through the apertured plug; a valve in each cylinder closure member, each valve being operative to permit fluid from the reservoir to enter the respective displacement chamber for replenishing iiuid losses therein; a plug immovably secured in the hollow rod substantially intermediate its ends, said plug having a diametral passage adjacent each end of the piston thereon communicatingwith the openings in the hollow rod; an axial recess in the plug extending from one end and communicating with both diametral passages; an annular ledge forming a valve seat in the plug recess between said two passages; a hollow valve slidably fitting in the recess of the plug, a portion of the inner end being of smaller outside diameter than the body of said valve so as to form an annular shoulder on the valve and an annular space between the valve and plug with which one diametral passage communicates, there being provided an outward annular flange at the extreme end of the valve, predeterminately larger in diameter than the said smaller diameter portion of the valve and smaller than the diameter of the recess in the plug, a side opening in the smaller diameter portion of said valve; a spring interposed between the adjustable plug in the rod and said valve operative yieldably to urge the outward annular flange on the valve upon the valve seat in the recess; an opening in the wall of the smaller diameter portion of the valve; a cupshaped plug secured Within the valve, said plug having two relatively predeterminately sized orices, one in its outer end wall, the other in its annular wall so as to communicate with the said side opening in the valve; and an oriiiced plug in the outer end of the valve recess.

9. A device in accordance with claim 8 in which the two orifices in the cup-shaped plug secured Within the valve are substantially identical in fiuid ow capacity; the orifice in the plug at the outer end of the valve recess being predeterminately smaller than said two orifices, and the annular shoulder provided between the larger and smaller outer diameter portions of the valve is of predeterminately greater area than the area of the annular flange engaging the valve seat Within the valve recess.

10. An hydraulic shock absorber comprising a cylinder; a fluid reservoir in communication with each end of the cylinder through a one-way valve; an imperforate piston forming two uid displacement chambers in the cylinder and having a hollow rod slidably supported in rod guides provided by end closure members of the cylinder; openings in the rod 0n each side of the piston providing communication between said displacement chambers; and fluid ow control mechanism within said hollow rod, said mechanism having a single, spring loaded, oriiiced valve urged into engagement with a valve seat in said hollow rod and operative rst through the orices and without moving, then movable from its seat in one direction only by iluid pressure resulting from piston reciprocation in either direction within the cylinder, for effecting predeterminately restricted transfer of fluid from one side of the piston to the other.

EDWIN F. ROSSMAN.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 2,148,839 Rossman et al Feb. 28, 1939 2,161,642 Stroup June `6, 1939 2,507,601 Kehle May 16, 1950 FOREIGN PATENTS Number Country Date 548,943 Great Britain Oct. 30, 1942 

